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Large temperature differences exist between the winter and summer seasons in different regions of China. Such temperature differences, caused by seasonal changes, may affect the life cycles of piles. Under natural conditions, such as long-term operation under the ambient environment and loads, piles and the surrounding soil undergo peel damage. To study such peel damage between the pile and soil at different temperatures, we installed concrete test piles in soil and subjected them to different temperatures. A crack with a width of 2 cm, depth of 10 cm, and damage range of 90° was applied at the side of the piles. Furthermore, a horizontal impact load was applied near the top of the pile and a piezoelectric ceramic sensor was used to obtain the stress wave response signals. The experimental results reveal that with a decrease in the soil temperature, the amplitude and fluctuation range of the signals received by the piezoelectric sensor decreased. According to the experimental results, in the group with the greatest influence of temperature, keeping other conditions unchanged and setting different crack depths, the horizontal impact load can also be introduced to observe the frequency change. It can be observed that the larger the crack depth, the smaller the frequency. Finally, ABAQUS was used for simulations, whose results were found to be consistent with those of the experiments. This paper describes a method for determining the safety of soil and piles with peel damage at different temperatures, and it also provides a validation of the necessity of holding the rest constant. [ABSTRACT FROM AUTHOR]

Considering the rapeseed planting area is large in hilly and montanic area and the planting period for rice and rapeseed is partly overlapped in flat area in China, a rapeseed aerial seeding device used for UAV was designed in this paper. The rapeseed aerial seeding device included two parts: seeding device and control system. The working power come from UAV. Structure parameters of seed box volume, seed-filling funnel and geneva wheel of aerial seeding device were confirmed. The volume of seed box was 5.2 L so that it provided enough rapeseed for UAV to seeding 0.67 hm2 area at one operation. The upper inlet shape of seed-filling funnel was a rectangle with length 30 mm and width 18 mm. The down outlet shape of seed-filling funnel was a circle with diameter 15 mm. The length of seed-filling funnel was 49-65 mm. The diameter of geneva wheel seed metering device was 80 mm with 30 type holes per circle in circumferential direction. Aerial seeding control system contained hand tele-control system and airborne tele-control system. The airborne tele-control system contained main controller (STM32 single chip), BeiDou Navigation chip, piezoelectric sensor, stepping motor with driver, flying information detection module, wireless transmission module and power module. The hand tele-control system contained controller, display screen, wireless transmission module, power module and keys. When the UAV was in the working field, the location information of UVA was detected by flying information detection module and the aerial seeding device started to seeding. The aerial seeding device stopped to seed when the flying information detection module detected that the UAV was out the working field. Hand tele-control system communicated with the airborne tele-control system acquired the flying information and then controlled the seeding rate of metering device when the UAV was flying. In order to analyze the factors affecting the working performance of aerial seeding device, the simulation model of airflow field of UAV rotor wing was established and the effects of rotor wing to airflow field was analyzed. The simulation results showed that the airflow field conducted by rotor wing affected the rapeseed falling track obviously. With the flight height of UVA increased, the range of space airflow field affected by UVA wings increased, and the distribution area of rapeseed landing on the ground increased. The relationship model between the UAV flight speed and geneva wheel rotary speed was established by selecting the length of seed-filling funnel and geneva wheel rotary speed as the factors based on the bench est. The results showed that when the distance between outlets of seed guiding tube and rotor wing was 300 mm, the length of seed-filling funnel was 53 mm, geneva wheel rotary speed was 10-50 r/min, the geneva wheel seeding rate met the requirements at the UAV flight speed of 2-4 m/s. The pavement test was conducted and the results showed that the effective working width was 2.15-2.45 m, coefficient of variation of seed distribution uniform was 32.05%-34.78% at the cross distance of seed tube outlets of 1.1 m, UAV flight height of 2-2.5 m. The average seedling density of field experiment was 64.5 plants/m², the coefficient of variation of seed distribution uniformity was 38.23%, which meet the requirements of rape cultivation This study can provide a reference for the design of UAV aerial seeding device. In order to further optimize the working performance of UAV aerial seeding, it is necessary to conduct comprehensive tests under natural wind and different field conditions in the future research work. [ABSTRACT FROM AUTHOR]

The swirl flowmeter is widely used in the wellhead measurement of low-permeability gas fields in China. In this study, the MEMS three-axis acceleration sensor (MEMS-TAAS) replaced the traditional piezoelectric sensor to distinguish the frequency signal from the interference noise. Based on the MEMS-TAAS, the vector acceleration signals of swirl flowmeter were acquired and analyzed simultaneously with the precession frequency signals to establish a wet gas two-phase flow measurement model. The method of establishing a liquid volume fraction prediction model based on the vector acceleration modulus parameter was pioneered. Finally, a dual-parameter wet gas measuring method under normal pressure was constructed using an iteration algorithm. The results demonstrate that this model's relative errors are acceptable. This method effectively provides further development thought for swirl flowmeter which can achieve the accurate prediction of two-phase flow using only one swirl meter with a MEMS-TAAS, without the need for other flow meters or differential pressure sensors, especially for the low-liquid-fraction wet gas. [ABSTRACT FROM AUTHOR]

Chinese liquors can be classified according to their flavor types. Accurate identification of Chinese liquor flavors is not always possible through professional sommeliers' subjective assessment. A novel polymer piezoelectric sensor electric nose (e-nose) can be applied to distinguish Chinese liquors because of its excellent ability in imitating human senses by using sensor arrays and pattern recognition systems. The sensor, based on the quartz crystal microbalance (QCM) principle is comprised of a quartz piezoelectric crystal plate sandwiched between two specific gas-sensitive polymer coatings. Chinese liquors are identified by obtaining the resonance frequency value changes of each sensor using the e-nose. However, the QCM principle failed to completely account for a particular phenomenon: we found that the resonance frequency values fluctuated in the stable state. For better understanding the phenomenon, a 3D Computational Fluid Dynamics (CFD) simulation using the finite volume method is employed to study the influence of the flow-induced forces to the resonance frequency fluctuation of each sensor in the sensor box. A dedicated procedure was developed for modeling the flow of volatile gas from Chinese liquors in a realistic scenario to give reasonably good results with fair accuracy. The flow-induced forces on the sensors are displayed from the perspective of their spatial-temporal and probability density distributions. To evaluate the influence of the fluctuation of the flow-induced forces on each sensor and ensure the serviceability of the e-nose, the standard deviation of resonance frequency value (SDF) and the standard deviation of resultant forces (SDFy) in y-direction (Fy) are compared. Results show that the fluctuations of Fy are bound up with the resonance frequency values fluctuations. To ensure that the sensor's resonance frequency values are steady and only fluctuate slightly, in order to improve the identification accuracy of Chinese liquors using the e-nose, the sensors in the sensor box should be in the proper place, i.e., where the fluctuations of the flow-induced forces is relatively small. This plays a significant reference role in determining the optimum design of the e-nose for accurately identifying Chinese liquors. [ABSTRACT FROM AUTHOR]